Access control method and apparatus of UE

ABSTRACT

A method for controlling delay tolerant access of a Machine-Type Communication (MTC) device based on a backoff mechanism is provided. The method includes receiving, at a terminal, a paging message including an access barring information update indicator from a base station, and receiving a System Information Block (SIB) including updated access barring information, the SIB being received regardless of modification periods. The terminal receives the SIB including the updated access barring information immediately without waiting for the arrival of next modification period, resulting in improvement of access barring efficiency.

PRIORITY

This application is a continuation application of prior application Ser.No. 13/461,970, filed on May 2, 2012, which claimed the benefit under 35U.S.C. §119(a) of a Korean patent application filed on May 2, 2011 inthe Korean Intellectual Property Office and assigned Serial No.10-2011-0041562, and a Korean patent application filed on Aug. 12, 2011in the Korean Intellectual Property Office and assigned Serial No.10-2011-0080685, the entire disclosure of each of which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for controlling a delaytolerant access of a Machine-Type Communication (MTC) device in a 3rdGeneration Partnership Project (3GPP) system. More particularly, thepresent invention relates to a backoff method for reducing wirelessnetwork overload caused by simultaneous attempts of a plurality of MTCdevices within a cell.

2. Description of the Related Art

Mobile communication systems have been developed to provide subscriberswith voice communication services on the move. With the advancement oftechnology, the mobile communication systems have been evolved tosupport high speed data communication services as well as standard voicecommunication services. Recently, a next generation mobile communicationsystem shifts its paradigm from Human to Human (H2H) to Machine toMachine (M2M). In order to meet this paradigm shift, the 3GPP hasstandardized the MTC.

The MTC has unique features as compared to normal wirelesscommunication. The features are variously categorized according to apurpose of the MTC. For example, some MTC devices require only a fewcommunication sessions per data regardless of time, and thuscommunication time has a delay-tolerant feature. Other MTC devices,installed at a fixed place to collect and transmit information withoutmobility, have a low mobility feature. A mobile carrier has to provideservice in consideration of a coexistence between both the MTC device aswell as a legacy User Equipment (UE).

A plurality of MTC devices may operate in one cell. Accordingly, whenmultiple MTC devices attempt to simultaneously access a network, theaccess may instantly cause an abrupt increase of a radio network load.Such an abrupt increase makes the radio network instable which resultsin an initial attachment failure of most MTC devices. Since most of theMTC devices are characterized by the delay-tolerant feature, it is notinevitable to establish a connection with a base station (evolved Node Bor eNB) immediately. If the network load exceeds a preset threshold, theeNB restricts the MTC devices' initial access to the network first inorder to control the overload. Recently, a method for extending anaccess barring mechanism has been introduced to control the networkload. A normal access barring mechanism operates by transmitting relatedinformation in a System Information Block (SIB).

However, it takes a relatively long time for the eNB to acquire the SIBafter its modification in structure. Accordingly, it is not efficient toadopt the normal access barring mechanism, without modification, to thewireless network in which traffic load increases abruptly.

Therefore, a need exists for a system and method for reducing a networkload.

SUMMARY OF THE INVENTION

Aspects of the present invention are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentinvention is to provide a random access method that is capable ofefficiently reducing a load of a Radio Access Network (RAN).

In accordance with an aspect of the present invention, a random accessexecution method of a terminal is provided. The method includesreceiving a paging message including an access barring informationupdate indicator from a base station, and receiving a System InformationBlock (SIB) including updated access barring information, the SIB beingreceived regardless of modification periods.

In accordance with another aspect of the present invention, a randomaccess execution method of a base station is provided. The methodincludes transmitting a paging message including an access barringinformation update indicator to a terminal, and transmitting a SIBincluding updated access barring information, the SIB being received bythe terminal regardless of modification periods.

In accordance with another aspect of the present invention, a terminalfor executing random access is provided. The terminal includes atransceiver for transmitting and receiving signals to and from a basestation, and a controller for controlling to receive a paging messageincluding an access barring information update indicator from a basestation and a SIB including updated access barring information, the SIBbeing received regardless of modification periods.

In accordance with still another aspect of the present invention, a basestation for executing random access is provided. The base stationincludes a transceiver for transmitting and receiving signals to andfrom a terminal, and a controller for controlling to transmit a pagingmessage including an access barring information update indicator to aterminal and a SIB including updated access barring information, the SIBbeing received by the terminal regardless of modification periods.

Other aspects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a diagram illustrating a normal System Information Block (SIB)transmission mechanism according to an exemplary embodiment of thepresent invention;

FIG. 2 is a signaling diagram illustrating a method for addressing aproblematic situation in a normal SIB transmission mechanism accordingto an exemplary embodiment of the present invention;

FIG. 3 is a signaling diagram illustrating an access control methodaccording to a first exemplary embodiment of the present invention;

FIG. 4 is a flowchart illustrating a User Equipment (UE) procedure of anaccess control method according to the first exemplary embodiment of thepresent invention;

FIG. 5 is a signaling diagram illustrating an access control methodaccording to a second exemplary embodiment of the present invention;

FIG. 6 is a flowchart illustrating a UE procedure of an access controlmethod according to the second exemplary embodiment of the presentinvention;

FIG. 7 is a signaling diagram illustrating an access control methodaccording to a third exemplary embodiment of the present invention;

FIG. 8 is a flowchart illustrating a UE procedure of an access controlmethod according to the third exemplary embodiment of the presentinvention;

FIG. 9 is a signaling diagram illustrating an access control methodaccording to a fourth exemplary embodiment of the present invention;

FIG. 10 is a flowchart illustrating a UE procedure of an access controlmethod according to the fourth exemplary embodiment of the presentinvention;

FIG. 11 is a block diagram illustrating a configuration of a UEaccording to an exemplary embodiment of the present invention; and

FIG. 12 is a diagram illustrating formats of an Extended Access Barring(EAB) category indicator for use in an access control method accordingto an exemplary embodiment of the present invention.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention is provided for illustration purpose only and not forthe purpose of limiting the invention as defined by the appended claimsand their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

Exemplary embodiments of the present invention provide a method forefficiently controlling Machine-Type Communication (MTC) devicesattempting a delay tolerant access in a 3rd Generation PartnershipProject (3GPP) system.

The exemplary embodiments of the present invention also provide a methodfor restricting simultaneous access of the MTC devices attempting accessto the network in order to prevent an overload.

A Release 11 (Rel-11) MTC issue has been discussed, which is focused ona Radio Access Network (RAN) overload. As one approach for addressingthe RAN overload, an Extended Access Barring (EAB) has been introduced.In the EAB, a new Access Class (AC) is provided for a delay tolerantaccess, i.e., MTC device, and thus all types of MTC devices may becategorized into the AC. In order to efficiently control initial accessof the MTC devices belonging to the AC, AC information is included in aSystem Information Block (SIB). Even in a case of not defining the newAC, it is defined for the MTC devices to receive the AC information.Typically, the AC information is included in a second SIB (SIB2). TheEAB introduced in the Rel-11 may be included in the SIB2 or a newlydefined SIB. In an exemplary embodiment of the present invention, theSIB including the EAB information is referred to as a SIBx.

The use of the normal SIB transmission mechanism for transmitting theEAB-related information in the SIBx has a problem in that it isdifficult to apply the AC immediately when the RAN overload is detected.

FIG. 1 is a diagram illustrating a normal SIB transmission mechanismaccording to an exemplary embodiment of the present invention.

Referring to FIG. 1, in a normal SIB transmission method, a modificationperiod concept is used. That is, the system notifies of an update ofSystem Information (SI) 100 using a paging message for the modificationperiod. If a SystemInfoModification Information Element (IE) is includedin the paging message, the updated SI 105 is transmitted in a nextmodification period. Although only one of several SI messages ischanged, this is indicated by the paging message. Exceptionally, if aSIB10 and SIB11 includes an Earthquake and Tsunami Warning System(ETWS), the SI can be updated regardless of the boundary of themodification period. If the paging message indicates the ETWS along withan ETWS-Indication IE, an evolved Node B (eNB) attempts to receive theSIB10 and SIB11 immediately. The length of a modification period isnotified by SIB2 and has a maximum value of 10.24 seconds. In a case ofusing a basic SIB transmission method without modification, the eNB hasto wait for the arrival of the next modification period after verifyingthe SI update in the paging message such that the initial accessattempts of the MTC devices continue until a new EAB is applied.

FIG. 2 is a signaling diagram illustrating a method for addressing aproblematic situation in a normal SIB transmission mechanism accordingto an exemplary embodiment of the present invention.

Referring to FIG. 2, an eNB 205 detects an abrupt overload of networktraffic at step 215 and thus restricts initial access attempts of theMTC devices at step 220 to control the network overload. For thispurpose, the eNB 205 transmits to a UE 200 a SystemInfoModification IEin a paging message at step 225. Upon receipt of the paging message, theUE 200 verifies the modification of the SIB in a next modificationperiod. However, since the SIB has not been received, the UE 200continues the initial access attempt based on basic information.Accordingly, the network overload is not alleviated until the nextmodification period 240 arrives. If the next modification period 240arrives, the UE attempts decoding on a SIB1 at step 245 because the SIB1contains scheduling information on another SIB. The UE 200 then receivesa SIBx including the EAB information at step 250. The eNB 200 mayacquire modified EAB information from the SIBx at step 225. In anexemplary embodiment of the present invention, a fast AC informationacquisition method that is capable of minimizing the AC informationacquisition delay is provided.

First Exemplary Embodiment

In a first exemplary embodiment of the present invention, the EABinformation change, such as the ETWS, is indicated in the pagingmessage. If a paging message including an indicator indicating the EABinformation change is received, the delay tolerant MTC device may stopthe use of the old EAB information and wait for acquiring new EABinformation. The MTC device may receive the SIBx scheduling informationincluding the EAB information from the SIB1 immediately without waitingfor the arrival of the next modification period to acquire theEAB-related information from the SIBx.

If the UE is not a MTC device but a normal device, the UE ignores thepaging message including the indicator related EAB information. The SIBxmeans a SIB including the EAB information. The MTC device determineswhether an access is permitted using the AC-related information. If theEAB information indicates an access is not permitted for the MTC device,the MTC device delays the attempt to access. Then, the MTC device wouldattempt an access again according to established methods. For examplethe MTC device may determine a backoff time and a delay random accesstransmission. Alternatively, the MTC device could delay the accessattempt until receives new EAB information lifted ban on access. If theEAB-related information has changed, the network informs of the changein the SIB information.

When the SI change information is received, the UE performs a normalinitial access procedure. That is, only when the EAB change informationis received, the MTC device takes a newly defined action. The firstexemplary embodiment of the present invention is implemented such thatthe UE receives the SIB in the paging message regardless of themodification period like the ETWS. However, the first exemplaryembodiment of the present invention has features different from theETWS.

The main difference is that the first exemplary embodiment of thepresent invention is applied to only MTC devices while the ETWS isapplied to normal devices. That is, although the paging messageincluding the EAB indicator according to the first exemplary embodimentof the present invention is received by a normal device, the deviceignores the SIB and thus the device does not progress to a next step.

Another difference is that the UE receiving the paging message includingthe ETWS indicator instructs a display of disaster information while theEAB indicator according to the first exemplary embodiment of the presentinvention instructs the UE to delay the random access transmission.

FIG. 3 is a signaling diagram illustrating an access control methodaccording to the first exemplary embodiment of the present invention.

Referring to FIG. 3, if it is determined to control an initialconnection of a MTC device (i.e., a UE equipped with Machine TypeCommunication) 305 due to a RAN overload, the eNB 310 transmits the UE305 a paging message including an EAB-indication IE at step 315. TheEAB-indication IE is used for informing of the change of the EAB-relatedinformation. If the EAB-indication is received, the UE 305 delays theaccess attempt until new EAB information is acquired at step 320.

In order to acquire the new EAB information, the UE 305 first receivesSIB1 information from the eNB 310 at step 325. The SIB1 informationincludes SIB scheduling information. By referencing the schedulinginformation, the UE 305 receives a SIBx including the EAB information atstep 330. The UE 305 applies the acquired EAB information at step 335and determines whether an access is allowed. Then, the UE 305 wouldattempt an access again according to established methods. For example,the EAB information could include an information needed for thecalculation a backoff time 340, as well as an information whether toallow an access. The UE 305 calculates a backoff time using the EABinformation in order to delay the access attempt during the backoff time340. After the backoff time has elapsed, the UE 305 attempts an initialaccess at step 345. Alternatively, the UE 305 could delay the accessattempt until receives new EAB information lifted ban on access. In anexemplary implementation, modification periods 350 and 355 are ignored.

FIG. 4 is a flowchart illustrating a UE procedure of an access controlmethod according to the first exemplary embodiment of the presentinvention.

Referring to FIG. 4, the UE is required to perform initial access to aneNB at step 400. The UE receives a paging message at step 405. Uponreceipt of the paging message, the UE determines whether the pagingmessage includes an EAB-indication IE at step 410. If the EAB-indicationis not included, the UE attempts random access instantly at step 455.The UE determines whether the access is attempted for delay tolerantaccess as a MTC device at step 413. Because the EAB information isadapted to delay tolerant access of the MTC devise, if the UE is not aMTC device, the UE attempts an access instantly at step 455. Otherwise,the UE delays the random access until the changed EAB information isacquired at step 415. The UE receives a SIB1 to acquire SIB schedulinginformation at step 420. The UE then receives a SIBx to acquire thechanged EAB information at step 425. The UE determines whether it isbarred at step 430. If it is determined that the UE is not barred atstep 430, the UE attempts random access at step 455. Otherwise, if it isdetermined that the UE is barred at step 430, the UE extracts a backoffparameter necessary for determining a backoff time and saves the backoffparameter at step 435. The UE then determines the backoff time to beactually applied using the backoff parameter at step 440. Next, the UEdelays the random access during the determined backoff time at step 445.After the backoff time expires, the UE attempts random access at step450. The procedure ends at step 460.

Second Exemplary Embodiment

In a second exemplary embodiment of the present invention, if theEAB-indication is received in the paging message, the UE delays randomaccess until the arrival of a next modification period. If the randomaccess is required, a delay tolerant MTC device waits for the nextmodification period and attempts random access by instantly applying thenew EAB information received in the next modification period rather thanthe current access information. That is, if an event triggering aninitial random access takes place, the UE waits for the nextmodification period to refresh the EAB information and attempts theinitial random access.

FIG. 5 is a signaling diagram illustrating an access control methodaccording to the second exemplary embodiment of the present invention.

Referring to FIG. 5, if it is determined to control an initial randomaccess of a MTC device (UE) 505 due to a network overload, the eNBtransmits a paging message including an EAB-indication IE to the UE 505at step 515. The EAB-indication IE is used for informing of the changeof the EAB-related information. If the EAB-indication is received, theUE 505 predicts receipt of new EAB information in a next modificationperiod 560 at step 520. The UE 505 delays random access until the newEAB information in a next modification period 560 at step 525. If theold modification period 555 has passed and the new modification period560 arrives, the UE 505 receives a SIB1 from the eNB 510 to acquire thenew EAB information at step 530. The SIB1 includes SIB schedulinginformation. By referencing the SIB1, the UE 505 receives a SIBxincluding EAB information at step 535. The UE 505 applies the newlyacquired EAB information at step 540 and determines a backoff time 545based on the EAB information to delay the random access during thebackoff time 545. After the backoff time has elapsed, the UE 505attempts an initial random access at step 550.

FIG. 6 is a flowchart illustrating a UE procedure of an access controlmethod according to the second exemplary embodiment of the presentinvention.

Referring to FIG. 6, the UE is triggered to perform an initial randomaccess to an eNB at step 600. Thereafter, the UE receives a pagingmessage at step 605. Upon receipt of the paging message, the UEdetermines whether the paging message includes an EAB-indication IE atstep 610. If it is determined that the EAB-indication is not included,the UE instantly attempts a random access at step 660. If it isdetermined that the EAB-indication is included, the EAB information haschanged. Accordingly, the UE delays the random access until new EABinformation is received in a next modification period at step 615. TheUE determines whether the next modification period has arrived at step620. If it is determined that the next modification period has arrived,the eNB transmits new EAB information and thus the UE receives a SIB1including SIB scheduling information at step 625. The UE then receives aSIBx to acquire the updated EAB information at step 630. The UEdetermines whether it is barred from accessing the eNB at step 635. Ifit is determined that the UE is not barred, the UE attempts the randomaccess at step 660. Otherwise, if it is determined that the UE isbarred, the UE extracts a backoff parameter necessary for determining abackoff time from the EAB information and saves the backoff parameter atstep 640. The UE determines the backoff time to be applied based on thebackoff parameter at step 645. The UE delays the random access duringthe determined backoff time at step 650. If the backoff time expires,the UE attempts the random access at step 655. The procedure ends atstep 665.

Third Exemplary Embodiment

In a third exemplary embodiment of the present invention, the EABinformation change is not explicitly notified, and the modificationperiod is not used. However, the SIBx including the EAB information istransmitted periodically unlike other SIBs. In an exemplaryimplementation, the modification period is referred to as a repetitionperiod. If it is necessary for the UE to perform the random access, therandom access is delayed until the SIB1 is received. The SIB1 mayinclude the scheduling information on the SIBx.

If the SIB1 does not include the SIBx scheduling information, the UE mayimmediately attempt the random access. If the SIB1 includes the SIBxscheduling information, the UE attempts the random access using the EABinformation updated based on the SIBx received by referencing thescheduling information. As a result, there is a drawback in that all ofthe UEs simultaneously attempt access at the SIB1 reception timing whenthe access barring is not executed. That is, the method according to thethird exemplary embodiment of the present invention may cause a wirelessnetwork overload at the SIB transmission timing Therefore, there is aneed for overcoming the drawback of the UE simultaneously attempting toaccess at the SIB1. One approach is to control such that the randomaccess is mandatorily attempted after a backoff time even when therandom access of the MTC device is not barred. Since the MTC device hasthe delay tolerant feature, the data transmission delay causes nosignificant problems. In order to determine the backoff time to beapplied for the initial access, the backoff-related information may beincluded in the SIBx. As a result, access of the MTC devices aredistributed such that the network load is balanced.

FIG. 7 is a signaling diagram illustrating an access control methodaccording to the third exemplary embodiment of the present invention.

Referring to FIG. 7, an eNB 710 periodically transmits a SIBx 720 basedon a repetition period 760. The repetition period is notified to the UE705 through the SIB1 715 and 735. If it is determined that an initialrandom access is necessary, the UE 705 delays the initial random accessto the next SIB1 reception timing 735. That is, if the SIB1 does notinclude scheduling information on the SIBx, the UE may immediately trythe initial access. In this case, a plurality of UEs attempt access tothe eNB to instantly increase the RAN load. In order to distribute theload, a short backoff operation may mandatorily be performed. The UE 705receives the SIBx at step 740 and applies the updated EAB informationacquired from the SIBx at step 745. The UE 705 delays the access attemptduring the backoff time 750 based on the EAB information. Finally, theUE 705 attempts the access at a time when the backoff time expires atstep 755.

FIG. 8 is a flowchart illustrating a UE procedure of an access controlmethod according to the third exemplary embodiment of the presentinvention.

Referring to FIG. 8, the UE receives information, i.e., periodinformation, necessary for acquiring a SIBx from a SIB2 at step 800. TheUE then determines whether to perform an initial access to the eNB atstep 805. At this time, the UE delays the initial access attempt untilchanged EAB information is acquired from the SIBx at step 810. The UEacquires the EAB information from the SIBx at step 815. The UEdetermines whether it is barred from accessing the eNB based on the EABinformation at step 820. If it is determined that the UE is not barredfrom accessing the eNB, the UE attempts access to the eNB at step 850.In order to distribute a load to overcome the aforementioned drawback,the access may be delayed during a relatively short backoff time at step845. The information for determining the backoff time may be provided inthe SIBx. If it is determined that the UE is barred from accessing theeNB, the UE saves the backoff parameter necessary for determining thebackoff time from the EAB information at step 825. The UE determines thebackoff time to be applied based on the backoff parameter at step 830.The UE then delays the access until the backoff time expires at step835. If the backoff time has expired, the UE attempts access to the eNBat step 840. The procedure ends at step 855.

Fourth Exemplary Embodiment

In a fourth exemplary embodiment of the present invention, the EABinformation is included in a paging message. The EAB information doesnot need a large amount of information. It is enough to secure theamount for including the information indicating access barring of theMTC device and backoff parameter necessary for determining the backofftime. Accordingly, it is not so burdensome to insert correspondinginformation into the paging message. If the paging message includes abarring indication, the MTC device backs off based on the EABinformation for initial access.

FIG. 9 is a signaling diagram illustrating an access control methodaccording to the fourth exemplary embodiment of the present invention.

Referring to FIG. 9, if it is determined to control an initialconnection of a MTC device (UE) 905 due to the RAN overload, the eNB 910transmits to the UE 905 a paging message including the EAB informationat step 915. Upon receipt of the EAB information, the UE 905 applies thenew EAB information for a preset time duration at step 920. If theinitial access is triggered in a preset time, the UE determines thebackoff time 925 based on the EAB information and delays an accessattempt for the backoff time 925. If the backoff time expires, the UEattempts a random access to the eNB 910 at step 930.

FIG. 10 is a flowchart illustrating a UE procedure of an access controlmethod according to the fourth exemplary embodiment of the presentinvention.

Referring to FIG. 10, the UE receives a paging message at step 1000. TheUE then determines whether the paging message includes EAB informationat step 1005. If the EAB information is not included and if an initialrandom access is required, the UE instantly attempts a random access atstep 1040. If the EAB information is included, the UE stores the EABinformation at step 1010. Valid EAB information is applied for a presettime duration. After storing the EAB information, the UE is required toattempt the initial random access to the eNB at step 1015. At this time,the UE determines whether the EAB information is valid at step 1020. Thevalidity of the EAB information is determined based on the preset timeduration. If the preset time elapses, the validity of the EABinformation is nullified. The UE determines a backoff time to be appliedusing the backoff parameter at step 1025. The UE delays random accessuntil the backoff time expires at step 1030. If the backoff timeexpires, the UE attempts random access to the eNB at step 1035. Theprocedure ends at step 1045.

FIG. 11 is a block diagram illustrating a configuration of a UEaccording to an exemplary embodiment of the present invention.

Referring to FIG. 11, the UE includes a controller 1100, a transceiver1105, a memory device 1110, and a measurer 1115. The controller 1100controls operations of the components. The controller 1100 decodes andanalyzes a paging message, a SIB1, and SIBx information received by thetransceiver 1105, controls the transceiver 1105 to transmit accessinformation stored in the memory device 1110, and controls the measurer1115 to collect data to be transmitted to an eNB and transfer thecollection information to the memory device 1110. The controller 1100also determines a backoff time using a backoff parameter received fromthe eNB and determines a random access attempt timing.

Although not illustrated, the eNB according to an exemplary embodimentof the present invention includes a transceiver and a controller. Thetransceiver transmits the paging message, the SIB1, and the SIBxinformation. The controller controls the transceiver to transmit the EABinformation to the UE which is waiting for the initial random accessattempt. At this time, the controller may determine whether to changepreconfigured EAB information. If it is necessary to change the EABinformation, the controller may transmit a paging message notifying theUE of the EAB information change such that the UE delays a random accessattempt. Also, if it is necessary to change the EAB information, the UEmay transmit a paging message including the EAB information.

The EAB information may be applied to all UEs, and the EAB informationmay be applied depending on a Public Land Mobile Network (PLMN) whichprovides service to the UE. Assuming that the EAB information iscategorized into one of three categories, a first category (category a)EAB information is applied to all of the UEs, a second category(category b) EAB information is applied to all of the UEs with theexception of the UEs served by a Home PLMN (HPLMN) and an equivalentPLMN (ePLMN), and a third category (category c) EAB information isapplied to all of the UEs with the exception of the UEs served by theHPLMN and ePLMN and roaming UEs. That is, the categories have therelationship of category a⊃category b⊃category c.

In order to reduce a RAN load, the eNB may restrict access of all MTCdevices by barring the UEs belonging to the first category. If it isdetermined to exclude the UEs connected to the HPLMN and ePLMN from theaccess barring list, the eNB may select the category b. Furthermore, ifit is determined to exclude the roaming UEs as well as the UEs connectedto the HPLMN and ePLMN from the access barring list, the eNB may selectthe category c. By controlling the random access of the UEs percategory, the access barring can be controlled based on the prioritiesof the UEs in view of the network operation. For category-based accesscontrol, the eNB has to notify the UE of the category of the EABinformation. The EAB information category may be indicated as describedbelow according to exemplary embodiments of the present invention.

In the first exemplary embodiment of the present invention, a newindicator for indicating the EAB category may be included in the pagingmethod along with the EAB-indication. In this case, if the pagingmessage is received, the UE determines whether to decode the SIBinformation for acquiring the EAB information based on the category towhich the UE belongs. Accordingly, it is possible to prevent the UEbelonging to the category, which is not a target for barring access,from unnecessarily decoding the EAB information. This is applied to thesecond exemplary embodiment of the present invention.

In the third and fourth exemplary embodiments of the present invention,the EAB-indication for notifying of the existence of EAB information isnot transmitted to the UE. In the third exemplary embodiment of thepresent invention, the eNB transmits to the UE the SIB including anindicator informing of the category of the EAB included in a specificSIB. In the fourth exemplary embodiment of the present invention, thepaging message includes the EAB information and corresponding indicator.

FIG. 12 is a diagram illustrating formats of an EAB category indicatorfor use in an access control method according to an exemplary embodimentof the present invention.

Referring to FIG. 12, reference numbers 1205, 1210, and 1215 denote theEAB category indicators informing of the respective EAB categories. TheEAB category indicator is a 2-bit value that discriminates among threecategories. For example, the reference number 1205 denotes the EABcategory indicator for indicating category a with a value of 01. Thereference number 1210 denotes the EAB category indicator for indicatingcategory b with the value of 10. The reference number 1215 denotes theEAB category indicator for indicating category c with the value of 11.

As described above, a random access method of an exemplary embodiment ofthe present invention enables a terminal to receive the SIB includingupdated access barring information immediately without waiting for thearrival of a next modification period, resulting in access barringefficiency.

In order to achieve efficient access barring, an indicator instructs theUE to receive the SIB immediately in a paging message.

Furthermore, the access control method and apparatus of an exemplaryembodiment of the present invention enable the eNB to restrict aninitial random access of the MTC devices first to efficiently controlthe RAN load.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the presentinvention as defined by the appended claims and their equivalents.

What is claimed is:
 1. A method by a base station in a communicationsystem, the method comprising: transmitting a paging message to anextended access barring (EAB) capable terminal, the paging messageincluding information indicating a change of EAB information;transmitting first system information including scheduling informationrelated to second system information without waiting until a next systeminformation modification period; and transmitting the second systeminformation including changed EAB information to the EAB capableterminal based on the scheduling information related to the secondsystem information.
 2. The method of claim 1, wherein previouslyreceived system information in the EAB capable terminal is discarded, ifthe scheduling information related to the second system information isnot included in the first system information.
 3. The method of claim 1,wherein the second system information includes first informationindicating at least one access class among a plurality of accessclasses.
 4. The method of claim 1, wherein the second system informationincludes second information indicating a category of terminals for whichthe changed EAB information is applied.
 5. The method of 4, wherein thecategory corresponds to one of a first category indicating allterminals, a second category indicating terminals with the exception ofterminals served by a home public land mobile network (HPLMN) and anequivalent PLMN, and a third category indicating terminals withexception of the terminals served by the HPLMN and the equivalent PLMN,and terminals related to roaming.
 6. The method of claim 1, wherein thechanged EAB information is not applied to the EAB capable terminal, ifat least one of an access class information and category information inthe second system information does not corresponds to the EAB capableterminal.
 7. A base station in a communication system, the base stationcomprising: a transceiver; and a controller configured to control thetransceiver to: transmit a paging message to an extended access barring(EAB) capable terminal, the paging message including informationindicating a change of EAB information, transmit first systeminformation including scheduling information related to second systeminformation without waiting until a next system information modificationperiod, and transmit the second system information including changed EABinformation to the EAB capable terminal based on the schedulinginformation related to the second system information.
 8. The basestation of claim 7, wherein previously received system information inthe EAB capable terminal is discarded, if the scheduling informationrelated to the second system information is not included in the firstsystem information.
 9. The base station of claim 7, wherein the secondsystem information includes first information indicating at least oneaccess class among a plurality of access classes.
 10. The base stationof claim 7, wherein the second system information includes secondinformation indicating a category of terminals for which the changed EABinformation is applied.
 11. The base station of claim 10, wherein thecategory corresponds to one of a first category indicating allterminals, a second category indicating terminals with the exception ofterminals served by a home public land mobile network (HPLMN) and anequivalent PLMN, and a third category indicating terminals withexception of the terminals served by the HPLMN and the equivalent PLMN,and terminals related to roaming.
 12. The base station of claim 7,wherein the changed EAB information is not applied to the EAB capableterminal, if at least one of an access class information and categoryinformation in the second system information does not corresponds to theEAB capable terminal.